1. Field of the Invention
The present invention relates to a fuel directing reaction device for a passive fuel cell, more particularly, for a direct-liquid fuel cell.
2. Description of Related Art
With the advancement of technology, the demand for energy is increasing. However, the excessive use of traditional fossil fuels has caused resource depletion problem and numerous environmental pollution associated with several climate issues, such as global warming. Therefore, it is necessary to develop an alternative and renewable energy having high efficiency and low emission, such as solar power, geothermal power, wind power, and fuel cells, etc. Fuel cells can convert chemical energy into electricity with high conversion efficiency based on simple operating principles. Therefore, it is considered to have the potential of being developed as a reliable power generator.
A fuel cell is a kind of power supply, which generates electricity from the conversion of chemical energy through electrochemical reactions. In the fuel cells, hydrogen-containing fuels, such as hydrogen gas, methanol, ethanol, natural gas or liquid gasoline, can be delivered into the anode, and then be oxidized and decomposed into hydrogen ions (protons) and electrons at the anode. The protons migrate through the proton exchange membrane to the cathode, and react with oxygen and electrons which are propelled from the anode to the cathode through an external circuit to form water by the reduction reaction. Because the products of the fuel cells are water and carbon dioxide, it is considered to be a clean, environmentally friendly, and sustainable energy source.
As the fuel cell, direct methanol fuel cell (DMFC) has been extensively developed as a portable power source in recent years. Unlike proton exchange membrane fuel cell (PEMFC) that uses hydrogen as a fuel, the advantage of employing DMFC is mainly due to the safety handling and storage convenience of methanol. However, in the development of the liquid-feed DMFCs, it is critical to enhance the flow velocity and the uniformity of methanol distribution for the improvement in the methanol utilization and reaction efficiency of the fuel cell. In general, the methanol fuel is delivered into the reaction zone by means of the microfluidic channel to participate in the electrochemical reactions. The microfluidic channels reported for the fuel cells in the conventional art include straight-type, grid-type, paralleled-type, interdigitated-type, and serpentine-type microfluidic channels. Nevertheless, those types of the microfluidic channels cannot effectively enhance the flow velocity and the uniformity of fuel distribution. In the current development of the fuel cells, successful removal of the gas products generated from the reactions is also important to improve the reaction efficiency of the fuel cells. Consequently, it is in urgent demand to resolve the above problems to heighten the efficiency of the fuel cells.